Synthesis and optimization of solar-aided conventional thermal power plants

Two semester projects in series (SS 2016 and WS 2016/2017)

Student: Jaksic Fran

Supervisor: Ligang Wang (ligang.wang@epfl.ch), Anna Sophia Wallerand (anna.wallerand@epfl.ch)

 

Concentrated solar thermal has been considered as the most significant means of utilizing solar energy. Different temperature levels can be reached by various concentrators, e.g., 420 C by parobolic trough and even higher by solar dish (700 C) and solar tower (1000 C); thus, concentrated solar thermal can be employed to effectively enhance wide ranges of highly heat-demanding chemical processes (e.g., hydrothermal gasification) for producing solar fuels and power generation systems for indirectly generating electricity. In this project, we mainly consider solar thermal for power generation.

Concentrated solar thermal can be coupled directly with a steam cycle for power generation; however, this direct coupling suffers from low conversion efficiency and requires enough thermal energy storage for ensuring a continous and stable operation. In this context, solar thermal integration into conventional thermal power plants, particularly pulverized-coal power plants (PCPP) and integrated gasification combined cycle (IGCC), has been widely investigated since 2008. The hybridization enable a further elevation of medium-grade concentrated heat by fossil fuels for reaching higher efficiency or a reduction of specific fossil fuel consumption when solar thermal serves as heat utility. Furthermore, the impact of intermittent nature of solar energy on grid stability can be significantly reduced by flexible load shifting of conventional thermal plants. Thus, this hybridization is very promising for large-scale high-efficient solar thermal utilization.

Previous publications on this topic mainly investigated different modes of integration, annual performance of different modes, and the evaluation of solar contribution. There is a lack of methodology or framework for optimal integrating solar thermal into PCPP and IGCC. In this project, we are going to handle this multi-time synthesis and optimization problem, which involves network designs (heat exchanger and steam turbine) as well as partial load operation.

Objective

To find the optimal grassroot and retrofit synthesis of solar thermal integration into PCPP and IGCC, considering multi-time heat-exchanger and steam-turbine network and partial load operation. 

Tasks

  • Build different flowsheets of solar-aided conventional thermal plants based on parobolic trough and solar tower technology
  • Evaluate different modes of integration and identify the solar contribution in power generation
  • Investigate the multi-objective multi-time synthesis of heat-exchanger and steam-turbine networks in closed cycle for grassroot design
  • Investigate the multi-objective multi-time integration of solar thermal into an existing PCPP and IGCC

Skill requirement

  • Solid understanding of heat-exchanger network and steam-turbine network design
  • Flowsheet softwares: Ebsilon professional or gPROMS
  • Integration software: OSMOSE LUA